Article

Feature Article
Nov 13, 2019 // 16 min read
Pre-Operative Analysis and Treatment Planning in Digital Implant Dentistry
Florian Kernen
Tabea Flügge
DOI: 10.3290/iti.fi.45646
Abstract

This article aims to give an overview of the application of digital technologies in implant dentistry. The workflow of digital imaging, computer-aided design and computer-aided manufacturing is followed with regard to implant dentistry.

In digital imaging, cone-beam computed tomography (CBCT) and optical surface scanning, including intraoral scanning and extraoral scanning of impressions or models are discussed. The advantages of direct digitization using intraoral scanners are contrasted by the lack of scientific data on the accuracy of these technologies in certain situations. CBCT is the clinical standard for three-dimensional imaging diagnostics, however, CBCT data are significantly compromised by imaging artifacts originating from dental restorations.

Computer-aided design (CAD) is used for virtual implant planning with regard to anatomical structures relevant to surgical implant placement and therefore to the long-term success of dental implants or the virtual design of implant-supported restorations. The acquired digital imaging data are used to virtually design the implant-supported restorations that are used for diagnosis and backward planning as well as possibly for the production of the final restorations on implants.

Computer-aided manufacturing is applied for the production of drill guides and implant-supported restorations. Additive and subtractive production technologies and available materials as well as their indications are the focus in this article.

Introduction

The introduction of digital technologies triggered the start of far-ranging changes in dental implantology. Digital imaging such as optical surface scanning and cone-beam computed tomography (CBCT), computer-aided design (CAD) and computer-aided manufacturing (CAM) allow for preoperative planning and the production of tools and components to achieve the planned treatment outcome (Fig. 1).

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Fig. 1: Digital workflow in dental implantology. a) diagnostic set-up; b) outline of the soft tissue; c) planned implant; d) mandibular canal

The intended implant position is defined in CBCT images while taking anatomical and prosthetic principles into consideration. According to the implant system and type, a drill guide hosting the respective drill sleeves is designed and may be produced using CAM. The correct fit and use of the drill guide and of each instrument in the drill sequence define the accuracy of the implant position. The use of drill guides to transfer the planned treatment to the surgical site is often termed ‘static computer-aided implant dentistry’ to differentiate it from navigated implant surgery, using an image-based navigation system with immediate feedback on the drill positions within the three-dimensional image of the patient.

A recent review systematically evaluated the literature regarding the accuracy and clinical outcome of static computer-aided implant dentistry (Tahmaseb et al. 2018). The review documented a mean error of 1.2 mm at the entry point of the implant, 1.4 mm at the apical point of the implant and a deviation of 3.5° for 2,136 implants. In order to understand why positional errors occur, the clinician must understand the limitations of each step of the digital workflow, including the planning and surgical process. From volumetric data acquisition using CBCT and optical surface scanning, through planning software (CAD), to drill-guide fabrication (CAM), each step can be a potential source of error in the digital workflow. This article focuses on each of the steps and highlights its challenges and limitations.